From mboxrd@z Thu Jan 1 00:00:00 1970 Return-path: Received: from mail-wm0-f68.google.com ([74.125.82.68]:35460 "EHLO mail-wm0-f68.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751208AbdBSS3G (ORCPT ); Sun, 19 Feb 2017 13:29:06 -0500 Received: by mail-wm0-f68.google.com with SMTP id u63so10765027wmu.2 for ; Sun, 19 Feb 2017 10:29:05 -0800 (PST) From: =?UTF-8?q?Frank=20Sch=C3=A4fer?= To: linux-media@vger.kernel.org Cc: mchehab@kernel.org, arnd@arndb.de, =?UTF-8?q?Frank=20Sch=C3=A4fer?= Subject: [PATCH 1/2] em28xx: reduce stack usage in sensor probing functions Date: Sun, 19 Feb 2017 19:29:17 +0100 Message-Id: <20170219182918.4978-1-fschaefer.oss@googlemail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Sender: linux-media-owner@vger.kernel.org List-ID: It's no longer necessary to keep the i2c_client in the device struct unmodified until a sensor is found, so reduce stack usage in em28xx_probe_sensor_micron() and em28xx_probe_sensor_omnivision() by using a pointer to the client instead of a local copy. Reported-by: Arnd Bergmann Signed-off-by: Frank Schäfer --- drivers/media/usb/em28xx/em28xx-camera.c | 42 +++++++++++++++----------------- 1 file changed, 20 insertions(+), 22 deletions(-) diff --git a/drivers/media/usb/em28xx/em28xx-camera.c b/drivers/media/usb/em28xx/em28xx-camera.c index 89c890ba7dd6..7b4129ab1cf9 100644 --- a/drivers/media/usb/em28xx/em28xx-camera.c +++ b/drivers/media/usb/em28xx/em28xx-camera.c @@ -110,44 +110,44 @@ static int em28xx_probe_sensor_micron(struct em28xx *dev) __be16 id_be; u16 id; - struct i2c_client client = dev->i2c_client[dev->def_i2c_bus]; + struct i2c_client *client = &dev->i2c_client[dev->def_i2c_bus]; dev->em28xx_sensor = EM28XX_NOSENSOR; for (i = 0; micron_sensor_addrs[i] != I2C_CLIENT_END; i++) { - client.addr = micron_sensor_addrs[i]; + client->addr = micron_sensor_addrs[i]; /* NOTE: i2c_smbus_read_word_data() doesn't work with BE data */ /* Read chip ID from register 0x00 */ reg = 0x00; - ret = i2c_master_send(&client, ®, 1); + ret = i2c_master_send(client, ®, 1); if (ret < 0) { if (ret != -ENXIO) dev_err(&dev->intf->dev, "couldn't read from i2c device 0x%02x: error %i\n", - client.addr << 1, ret); + client->addr << 1, ret); continue; } - ret = i2c_master_recv(&client, (u8 *)&id_be, 2); + ret = i2c_master_recv(client, (u8 *)&id_be, 2); if (ret < 0) { dev_err(&dev->intf->dev, "couldn't read from i2c device 0x%02x: error %i\n", - client.addr << 1, ret); + client->addr << 1, ret); continue; } id = be16_to_cpu(id_be); /* Read chip ID from register 0xff */ reg = 0xff; - ret = i2c_master_send(&client, ®, 1); + ret = i2c_master_send(client, ®, 1); if (ret < 0) { dev_err(&dev->intf->dev, "couldn't read from i2c device 0x%02x: error %i\n", - client.addr << 1, ret); + client->addr << 1, ret); continue; } - ret = i2c_master_recv(&client, (u8 *)&id_be, 2); + ret = i2c_master_recv(client, (u8 *)&id_be, 2); if (ret < 0) { dev_err(&dev->intf->dev, "couldn't read from i2c device 0x%02x: error %i\n", - client.addr << 1, ret); + client->addr << 1, ret); continue; } /* Validate chip ID to be sure we have a Micron device */ @@ -197,7 +197,6 @@ static int em28xx_probe_sensor_micron(struct em28xx *dev) dev_info(&dev->intf->dev, "sensor %s detected\n", name); - dev->i2c_client[dev->def_i2c_bus].addr = client.addr; return 0; } @@ -213,30 +212,30 @@ static int em28xx_probe_sensor_omnivision(struct em28xx *dev) char *name; u8 reg; u16 id; - struct i2c_client client = dev->i2c_client[dev->def_i2c_bus]; + struct i2c_client *client = &dev->i2c_client[dev->def_i2c_bus]; dev->em28xx_sensor = EM28XX_NOSENSOR; /* NOTE: these devices have the register auto incrementation disabled * by default, so we have to use single byte reads ! */ for (i = 0; omnivision_sensor_addrs[i] != I2C_CLIENT_END; i++) { - client.addr = omnivision_sensor_addrs[i]; + client->addr = omnivision_sensor_addrs[i]; /* Read manufacturer ID from registers 0x1c-0x1d (BE) */ reg = 0x1c; - ret = i2c_smbus_read_byte_data(&client, reg); + ret = i2c_smbus_read_byte_data(client, reg); if (ret < 0) { if (ret != -ENXIO) dev_err(&dev->intf->dev, "couldn't read from i2c device 0x%02x: error %i\n", - client.addr << 1, ret); + client->addr << 1, ret); continue; } id = ret << 8; reg = 0x1d; - ret = i2c_smbus_read_byte_data(&client, reg); + ret = i2c_smbus_read_byte_data(client, reg); if (ret < 0) { dev_err(&dev->intf->dev, "couldn't read from i2c device 0x%02x: error %i\n", - client.addr << 1, ret); + client->addr << 1, ret); continue; } id += ret; @@ -245,20 +244,20 @@ static int em28xx_probe_sensor_omnivision(struct em28xx *dev) continue; /* Read product ID from registers 0x0a-0x0b (BE) */ reg = 0x0a; - ret = i2c_smbus_read_byte_data(&client, reg); + ret = i2c_smbus_read_byte_data(client, reg); if (ret < 0) { dev_err(&dev->intf->dev, "couldn't read from i2c device 0x%02x: error %i\n", - client.addr << 1, ret); + client->addr << 1, ret); continue; } id = ret << 8; reg = 0x0b; - ret = i2c_smbus_read_byte_data(&client, reg); + ret = i2c_smbus_read_byte_data(client, reg); if (ret < 0) { dev_err(&dev->intf->dev, "couldn't read from i2c device 0x%02x: error %i\n", - client.addr << 1, ret); + client->addr << 1, ret); continue; } id += ret; @@ -309,7 +308,6 @@ static int em28xx_probe_sensor_omnivision(struct em28xx *dev) dev_info(&dev->intf->dev, "sensor %s detected\n", name); - dev->i2c_client[dev->def_i2c_bus].addr = client.addr; return 0; } -- 2.11.0